Smoking Article

ABSTRACT

There is provided a smoking article, comprising: an inner rod of aerosol generating material; an inner wrapper, circumscribing the inner rod; and a combustible outer rod circumscribing the inner wrapper, wherein combustion of the outer rod is arranged to heat the inner rod to generate an aerosol for delivery through the inner rod.

FIELD OF THE INVENTION

The present invention relates to a smoking article, for example aHeat-Not-Burn (HNB) device.

BACKGROUND

Heat-Not-Burn (HNB) devices which are sometimes also referred to asnon-combustion type smoking articles are being developed as a possiblealternative to conventional cigarettes. HNB technology generates anaerosol by heating rather than burning tobacco and/or other smokingmaterials. Examples of coaxial HNB cigarettes are known from USPublication No. US 2005/0066985 and U.S. Pat. No. 5,265,626.

A disadvantage of known HNB products, for example Premier™ and Eclipse™introduced by RJ Reynolds Tobacco Company is that they do not provide asimilar user experience to conventional tobacco burning cigarettes. Forexample, the above HNB products look, feel and taste different toconventional cigarettes.

SUMMARY

According to the invention there is provided a smoking article,comprising: an inner rod of aerosol generating material; a innerwrapper, circumscribing the inner rod; and a combustible outer rodcircumscribing the inner wrapper, wherein combustion of the outer rod isarranged to heat the inner rod to generate an aerosol for deliverythrough the inner rod.

Advantageously the aerosol is generated through heating but not burningthe inner rod. In addition, combustion of the outer rod provides avisual indictor of consumption to the user.

Conveniently, the inner wrapper is substantially non-flammable. This canhelp prevent combustion of the inner rod.

The inner wrapper may be substantially non-permeable.

Preferably, the smoking article comprises a central low impedance pathwhich is surrounded by a high impedance path.

Typically, the outer rod is of a higher density than the inner rodcreating a pressure drop to control airflow through the inner rod.

Preferably, the smoking article further comprises a filter arranged tocreate a pressure drop by having portions of varying density in thefilter to control airflow through the inner rod.

Optionally, airflow is restricted to flow through the inner rod only.

The inner wrapper may comprise bands, spaced along the length of theinner wrapper, wherein the bands are arranged to enable the inner rod tobreak and be disposed of along with ash from the outer rod.

The inner rod can have break portions, spaced along the length of theinner rod, the break portions becoming brittle when heated to enable theinner rod to break and be disposed of along with ash from the outer rod.

Typically, the aerosol generating material and/or the combustiblematerial of the outer rod is tobacco or a tobacco substitute.

The aerosol generating material can include additives, includinghumectants, and may be substantially non-combustible. Advantageously,humectants may i) prevent or arrest combustion of the inner rod, ii)contribute to the flavour and sensory experience for the consumer, andiii) prevent the aerosol generating material from drying out.

The invention also includes a method of manufacturing a smoking articledescribed above.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofillustrative example with reference to the accompanying drawings, inwhich:

FIG. 1 a is a perspective view of a coaxial smoking article showinginternal features of a body of the smoking article, including an innerrod and inner wrapper, in dashed lines.

FIG. 1 b is transverse cross-sectional view of the body of coaxialsmoking article of FIG. 1;

FIG. 2 is a longitudinal cross-sectional view of the coaxial smokingarticle of FIG. 1, showing an expanded view of a coaxial rod arrangementof the body;

FIG. 3 a is the longitudinal cross-sectional view of FIG. 2, showing anexpanded view of a filter arrangement for the smoking article;

FIG. 3 b is the longitudinal cross-sectional view of FIG. 2, showing anexpanded view of an alternative filter arrangement to that of FIG. 3 a;and

FIG. 4 is a longitudinal cross-sectional view of the coaxial smokingarticle of FIG. 1, part way though consumption.

FIGS. 1 a, 1 b and 2 show a coaxial smoking article 1, referred tohereinafter as a cigarette, that has a body 2 and a filter 4. The body 2of the cigarette is of coaxial construction and has an inner rod 6, aninner wrapper 8, an outer rod 10 and an outer wrapper 12.

DETAILED DESCRIPTION

The inner rod 6 of the coaxial arrangement contains tobacco or a tobaccosubstitute. The inner rod 6 is heated during use to cause volatilisationof low boiling point components within the product, while avoidingpyrolysis or combustion of the tobacco or volatiles. This volatilisationleads to the creation of a vapour which is drawn through the cigarette 1and is then condensed into an aerosol and inhaled by the consumer. Thevolatilised components include water, nicotine, humectants and lightvolatiles.

The inner rod 6 preferably contains a blend of tobacco or tobaccosubstitute which has been specifically formulated for the coaxial HNBcigarette although existing tobacco blends or tobacco substitutes may beused for the inner rod 6.

The tobacco blend of one embodiment may include additives which areincluded to enhance the sensorial attributes of the aerosol. Forexample, additives such as propylene glycol, glycerol or triacetin maybe added to the tobacco blend.

The inner rod 6 may also contain tobacco substitutes such as Baltec,Fibex or recon sheet or paper.

The blend of tobacco or tobacco substitutes used in the inner rod 6 ischosen to prevent or impede combustion of the inner rod 6. In oneembodiment, the blend is high in humectants to fulfil this function ofpreventing or impeding combustion. Humectants have an additional benefitof enhancing the aerosol produced by the inner rod 6 when heated whichin turn may improve the sensory experience of the HNB cigarette of thepresent embodiment. High levels of humectants in the inner rod 6 maycompletely prevent combustion of the inner rod 6.

Humectants, when added to the tobacco or tobacco substitute have afurther benefit of preventing the tobacco from becoming too dry.

The inner rod 6 is circumscribed by the inner wrapper 8, as shown inFIGS. 1 a, 1 b and 2. The inner wrapper 8 is a non-permeable orsemi-permeable material, which prevents or impedes gas or vapours frombeing drawn into the inner rod 6 along the length of the cigarette.

In addition, the inner wrapper 8 of one embodiment is non-flammable, oris of sufficiently low flammability to prevent or arrest combustion ofthe inner rod 6.

The inner wrapper of one embodiment is a cigarette paper having the oneor more of the above properties.

The inner rod 6 and inner wrapper 8 are circumscribed by the outer rod10, as shown in FIGS. 1 a and 1 b. The outer rod 10 comprises acombustible material, such as tobacco or a tobacco substitute, which iscombusted during use.

Combustion of the outer rod 10 leads to heating of the inner rod 6 whichin turn generates the aerosol for delivery to the consumer. The qualityof the material of the outer rod 10 need not be as high as the qualityof the inner rod, since the primary function of the outer rod 10 is notto provide the aerosol to the consumer, but rather is to heat the innerrod 6 for that purpose.

The outer rod 10 is circumscribed by the outer wrapper 12. In oneembodiment, the outer wrapper 12 is a conventional cigarette paper.

The construction of the inner rod 6, inner wrapper 8, outer rod 10 andouter wrapper 12, in one embodiment, may be achieved throughconventional coaxial cigarette manufacturing technology and is notdiscussed herein in any further detail.

As shown in the figures, the filter 4 is situated at the mouth end ofthe cigarette. During use, air from the body 2 of the cigarette 1 isdrawn into the consumer's mouth through the filter 4. In one embodiment,the filter 4 is made of cellulose acetate.

The filter 4 can be designed to control the airflow through thecigarette 1 as the consumer inhales through the cigarette 1. In oneembodiment, as shown in FIG. 3 a, airflow, depicted by arrow 14, throughthe body 2 of the cigarette 1 is through the inner rod 6 only, such thatno airflow or aerosol is derived from the combustible outer rod 10.

In an alternative embodiment, shown in FIG. 3 b, a major airflow,depicted by arrow 16, is through the inner rod 6, while a minimalairflow, depicted by arrows 18, is drawn from the combustible outer rod10.

In both embodiments, the majority of the aerosol drawn into theconsumer's mouth is derived from the inner rod 6. This is because thesmoking article has a low-impedance path which is surrounded by ahigh-impedance path.

In one embodiment, control of the airflow 14, 16, 18 is achieved bydeveloping a pressure drop between the inner rod 6 and outer rod 10,such that the airflow through the cigarette 1 flows through the innerrod 6 by following the path of least resistance.

The pressure drop can be manipulated as a result of different densitiesof the materials used in the inner rod 6 and the outer rod 10. Forexample, when the inner rod 6 has a lower density than an outer rod 10,airflow through the inner rod 6 is at a higher rate than through theouter rod 10.

In addition to, or independently of, the variations in the density ofthe inner and outer rods 6, 10, the filter 4 is also arranged to providethe desired pressure drop. As shown in FIGS. 3 a and 3 b, the filter 4has a central portion 20 and an outer portion 22 of different densities.As such, airflow through the central portion 20 is greater than throughthe outer portion 22 because the central portion 20 has a lower densitythan the outer portion 22.

The low-impedance and high impedance paths may be generated as a resultof the different densities of the inner and outer rods and/or as aresult of the above filter arrangement.

A person skilled in the art will be able to envisage a number ofpotential filter arrangements which will enable development of apressure drop. One such arrangement, shown in FIGS. 3 a and 3 b,comprises a substantially cylindrical filter portion, as the centralportion 20, having a tapered end closest to the body of the cigarette.The tapered end of the central portion is arranged to fit against arecess in a filter ring, being the outer portion 22, which abuts thebody 2 of the coaxial cigarette 1. Alternatively, the outer portion/ring22 may be integrally formed in the filter and arranged to have a higherdensity than the central portion 20 during manufacturing of the filterweb.

The pressure drop of the inner rod 6, outer rod 10 and filter 8arrangement is manipulated to maximise the flow down the inner rod 6.However, it may not be necessary for the airflow 14 to be wholly alongthe inner rod 6 and some of the vaporous products produced by combustionof the outer rod 10 may be utilised to contribute to the flavour and thesensory experience for the consumer.

Ventilation in the filter 4 or in the body 2 of the cigarette 1 mayincrease the rate of airflow though the inner rod 6 to ensure a suitableaerosol is delivered to the consumer. Such ventilation may befacilitated by providing perforations in tipping paper and plug wrapcircumscribing the filter, in the outer wrapper, and/or in the innerwrapper.

Use of the cigarette 1 will now be explained in more detail withreference to FIG. 4. Initially, a consumer lights a tip end 30 of thecigarette using conventional lighting means such as a match or acigarette lighter. The lighting means applied to the tip end 30 causesthe outer rod 10 at the tip end and the surrounding outer wrapper 12 tostart to combust. During this lighting action the inner rod 6 willeither fail to combust, or if combustion does commence, the inner rod 6will not continue to combust. The blend of tobacco or tobacco substitutein the inner rod 6 is designed to arrest or prevent combustion of theinner rod 6.

Combustion of the outer rod 10 provides heat to the inner rod 6 which inturn volatises nicotine and flavour components from the inner rodtobacco or tobacco substitute without combustion of the inner rod 6. Thevolatiles are transported through the inner rod 6, from the tip end andare inhaled by the consumer through the filter 4.

Combustion of the outer rod 10 happens gradually from the tip end 30toward the filter 4. Combustion happens at a particular burn rate toensure that the aerosol, including nicotine and flavour components, isdelivered to the consumer throughout consumption.

FIG. 4 shows the cigarette 1 part way through consumption. As shown, anash portion 34 of the outer rod has already combusted and has turned toash, and a combusting portion 36 of the outer rod 10 is in the processof combusting. Heat from this combusting portion 36 is transferredthrough the inner wrapper 8 to heat a corresponding portion 38 of theinner rod 6. When this corresponding portion 38 of the inner rod 6reaches a volatising temperature, the corresponding portion 38 of theinner rod generates the aerosol, as described above, which is inhaledthrough the inner rod 6 into the consumer's mouth. The heat transfer isthrough conduction as shown by the arrows 40 in FIG. 4.

A distal end 42 of the combusting portion 36 turns to ash, while heatfrom the combusting portion 36 causes the outer rod 10 to continue tocombust. In other words, heat from the portion 36 of the outer rod whichis in the process of combusting travels along the length of thecigarette from the tip end 30 toward the filter 4. As such, heat fromthe corresponding portion 38 of the inner rod also travels toward thefilter as the outer rod 10 is combusted, ensuring that the inner rod 6delivers the aerosol throughout the smoking process.

Ash from the ash portion 34 of the outer rod 10 may naturally fall fromthe cigarette 1. Advantageously, this provides a visual indicator ofconsumption to the consumer.

In one embodiment, the inner rod 6 is banded with break portions, alongthe length of the cigarette. The break portions become brittle whenheated, and are arranged to cause the inner rod 6 to break so that usedportions of the inner rod (i.e. portions which have been heated andvolatised) may be disposed of along with the ash from the outer rod.

In addition, or alternatively, the inner wrapper 8 is banded withinflammable bands which are spaced along the length of the cigarette 1.These bands help to cause breakage of the inner rod 6 so that usedportions of the inner rod may be disposed of along with the ash from theouter rod.

A person skilled in the art will appreciate that features ofconventional cigarettes may also be included in the cigarette 1, suchfeatures including conventional outer cigarette paper, plugwrap, tippingpaper and suitable ventilation.

A person skilled in the art will also appreciate that additives otherthan humectants may be used on the tobacco to enhance the aerosol and/orto prevent or impede combustion of the inner rod.

1. A HNB smoking article, comprising: an inner rod of aerosol generatingmaterial; an inner wrapper, circumscribing the inner rod; and a tobaccocontaining combustible outer rod circumscribing the inner wrapper,wherein combustion of the outer rod is arranged for heating but notcombusting the inner rod to generate an aerosol for delivery through theinner rod, and wherein a central low impedance path is presented fordelivery of the aerosol from the inner rod and an outer high impedancepath is presented for products of combustion of the outer rod.
 2. Thesmoking article of claim 1, wherein the inner wrapper is substantiallynon-flammable.
 3. The smoking article of claim 1, wherein the innerwrapper is substantially non-permeable.
 4. (canceled)
 5. The smokingarticle of claim 1, wherein the outer rod is of a higher density thanthe inner rod to create a pressure drop to control airflow through theinner rod.
 6. The smoking article of claim 1, further comprising afilter having portions of varying density arranged to create a pressuredrop in the filter to control airflow through the inner rod.
 7. Thesmoking article of claim 1, wherein airflow is restricted to flowthrough the inner rod only.
 8. The smoking article of claim 1, whereinthe inner wrapper comprises bands, spaced along the length of the innerwrapper, wherein the bands are arranged to enable the inner rod to breakand be disposed of, along with ash from the outer rod.
 9. The smokingarticle of claim 1, wherein the inner rod comprises break portions,spaced along the length of the inner rod, the break portions becomingbrittle when heated to enable the inner rod to break and be disposed of,along with ash from the outer rod.
 10. The smoking article of claim 1,wherein the aerosol generating material comprises one of tobacco and atobacco substitute.
 11. (canceled)
 12. The smoking article of claim 1,wherein the aerosol generating material comprises additives.
 13. Thesmoking article of claim 1, wherein the outer rod comprises one oftobacco and tobacco substitute.
 14. A method of manufacturing a HNBsmoking article comprising: providing an inner rod of aerosol generatingmaterial; wrapping an inner wrapper around at least a portion of theinner rod; and enclosing the inner rod substantially within a tobaccocontaining combustible outer rod, to form a central low impedanceaerosol delivery path for delivery of aerosol from the inner rod and anouter high impedance path for products of combustion of the outer rod.15. The method of claim 14, further comprising: wrapping an outerwrapper around at least a portion of the outer rod and a filter havingportions of varying density that control airflow through the inner rodto create a pressure drop.
 16. The smoking article of claim 12, whereinthe additives include humectants.